Fixed stuttering sound with 3.0.2 and Leopard

Flaffer · Joined: 02 Oct 2007 Posts: 8

The latest Quicktime update (version 7.4.1) caused all kinds of dropouts and stuttering sound. I followed directions at Macfixit to downgrade Quicktime to 7.3.1 and the problem is solved!

Here are the instructions:

1) Download [url=http://www.versiontracker.com/dyn/moreinfo/macosx/12743]Pacifist[/url].
2) Download the Quicktime 7.3.1 installer from Apple downloads.
3) Mount the Quicktime installer dmg.
4) Open Pacifist. Click 'Install'.
5) Follow the directions. Make sure you 'Use Administrator Privileges' when installing, as well as overwriting any files it prompts for.
6) Fixed!

Admin · Posted: Fri May 16, 2008 12:29 pm Post subject:

Hi Flaffer,

We've also recently discovered a problem with an AirPort Extreme software update, which has similar symptoms - I wonder if this could be related to the problem you discovered? It only affects Mac OS 10.4.11 on an Intel Mac.

Here's a description of the problem, together with a fix (also via Pacifist):

http://www.dj1800.com/tigerproblem.php

Thanks for taking the time to post your own discovery!

All the best,

Dave.

Flaffer · Joined: 02 Oct 2007 Posts: 8

I also found out another possible cause: with the Macbook, there seems to be two different paths for each USB port. When I plug into one of the ports, I can get the problem to show up (though it also showed up related to the QT issue) but it works perfectly fine in the other port. There must be a bandwidth issue with the one port (possibly one is "closer" to the CPU then the other?).

Thanks for the response.

Admin · Posted: Fri May 16, 2008 1:25 pm Post subject:

Hi Flaffer,

Interesting! Just to be clear, which problem are you seeing in relation to the two USB ports? Do you mean the "AirPort Extreme 2008-001" problem, or the QuickTime problem you mentioned before?

Out of interest, which MacBook do you have?

Dave.

Flaffer · Joined: 02 Oct 2007 Posts: 8

Sorry for not being clear: the stuttering issue was related to the QT issue (or the 10.5.2 update; I have not tried to figure it out because I have a working setup, so do not want to mess it up)! Later on, the problem came back and that it when I figured out the differing performance depending on which USB port I plugged into.

I am using the black Macbook. One issue is that the Macbook does not have USB 2 so doing both control and output seems to run a fine line to having just enough bandwidth and not having enough. I may pull up the board schematics and see if there is an obvious difference in where the USB bus runs.

Btw, since I am using Leopard, the Airport issue does not apply.

sqook · Joined: 19 Nov 2004 Posts: 127 Location: Sweden

[quote="Flaffer"]
I am using the black Macbook. One issue is that the Macbook does not have USB 2 so doing both control and output seems to run a fine line to having just enough bandwidth and not having enough. I may pull up the board schematics and see if there is an obvious difference in where the USB bus runs.
[/quote]

What? The macbooks definitely [url=http://www.apple.com/macbook/specs.html]do have USB2.0[/url]. If your device is USB1.0/1, then it will run in USB1 compatibility mode.

Also, IIRC, the 2 USB ports are on separate busses, so this should minimize bandwidth issues. At least, that's the way it is on the MBP... you can check out the system profiler to make sure.

[quote]
Btw, since I am using Leopard, the Airport issue does not apply.[/quote]

This issue might effect Leopard as well:

[url]http://createdigitalmusic.com/2008/05/12/fix-for-mac-audio-dropouts-roll-back-tiger-airport-support/[/url]

Admin · Posted: Fri May 16, 2008 2:18 pm Post subject:

Hmm, it's a tricky one. Whilst there's a definite "cause and effect" for 10.4.11, it doesn't seem so clear cut for 10.5.

What I'm doing now (it's a slow process) is to create a test install of 10.5.0, which I can incrementally upgrade until if / when I hear the same kinds of problems with 10.5.2. (If indeed I do get them at all.) I'm testing on a 2.4GHz Intel Core 2 Duo MacBook Pro, with 17" screen. I'll keep you posted.

Dave.

Flaffer · Joined: 02 Oct 2007 Posts: 8

[quote="sqook"][quote="Flaffer"]
IWhat? The macbooks definitely [url=http://www.apple.com/macbook/specs.html]do have USB2.0[/url]. If your device is USB1.0/1, then it will run in USB1 compatibility mode.
[/quote]

I do not believe this is true with my Macbook (bought about 1 year ago). If I look in SystemProfiler, the contoller is under a "USB Bus" which has a speed up to 12Mb/sec. The only "High-Speed Bus" is the "Built-In iSight" which has speed up to 480Mb/s. Neother of the ports I plug into load it into the USB 2 Device Tree (which is really dumb on Apple's part).

And i think this leads to the issue: when I plug into the back USP port, it shows up as being on the same bus as Keyboard/Trackpad. This may explain the bandwidth issues: it is USB 1 (or whatever the 12Mb/s speed designates) and if you are sharing the bus with the keyboard, it causes the bandwidth issues.

[quote]Also, IIRC, the 2 USB ports are on separate busses, so this should minimize bandwidth issues. At least, that's the way it is on the MBP... you can check out the system profiler to make sure.[/quote]

You are right. If I plug it into the Bus with no other devices on it, I do not run into any issues with the stuttering/droputs and sometimes even software lockups.

[quote]
Btw, since I am using Leopard, the Airport issue does not apply.[/quote]

[quote]This issue might effect Leopard as well:

[url]http://createdigitalmusic.com/2008/05/12/fix-for-mac-audio-dropouts-roll-back-tiger-airport-support/[/url][/quote]

I downgraded from 10.5.2 as well as stayed at a lwoer version of QT; I did this at the same time, so I am not sure if it is 10.5.2 ot latest QT update that caused the original issue. So right now, if I plug into the right USB port, I have no issues.

Admin · Posted: Fri May 16, 2008 9:29 pm Post subject:

Hi Flaffer,

I think you might be onto something here - or at least, other people are having different audio experiences with different USB ports under 10.5.2, including with other real-time audio applications:

http://www.m-audio.com/index.php?do=support.faq&ID=685d4c00fca59d8f3679660652bc9655

http://blogs.zdnet.com/Apple/?p=1717

http://forums.logitech.com/logitech/board/message?board.id=headsets_general&thread.id=3878

http://www.scratchlive.net/forum/discussion/?discussion_id=78923

It seems to be that some of the ports are on an internal USB Hub, whereas others are not. Presumably this affects the power available to certain ports, which in turn affects the performance of audio devices attached to the ports.